Exhaust fan



FIG. 1 is a first perspective view of an exhaust fan;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a third perspective view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a right side view thereof;

FIG. 8 is a top view thereof; and,

FIG. 9 is a bottom view thereof.

The broken lines in the figures depict portions of the exhaust fan that form no part of the claimed design. 

CLAIM The ornamental design for an exhaust fan, as shown and described. 